This application claims the priority of German Application No. 10 2004 021356.9 filed Apr. 26, 2004, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an open-end spinning rotor comprising a hollow interior, which is defined by an inner contour, which—starting from an opening width which is formed in the front surface by an opening—passes into a fiber collecting groove via a smooth fiber sliding surface extending conically, which fiber collecting groove has the largest diameter of the inner contour, which measures less than 30 mm.
An open-end spinning rotor of this embodiment is prior art in German published patent 41 23 255. Required speeds today for open-end spinning rotors presently exceed 150,000 rpm. For this reason, the dimensions of the open-end spinning rotors are designed as small as possible. However, the width of the opening located in the front surface must still permit the insertion of a component into the hollow interior, which component comprises the mouth of a fiber feed channel and the initial part of a yarn withdrawal channel, as a rule in the form of a yarn withdrawal nozzle. With the reduction of the dimensions of the open-end spinning rotor, practical operating limits are approached.
It is an object of the present invention to further optimize an open-end spinning rotor of the above mentioned type and to make it applicable for speeds which could reach 180,000 rpm.
This object has been achieved in accordance with the present invention in that—with an opening width of less than 24 mm—the tapering of the fiber sliding surface measures a maximum of 10°.
The aim of a compromise of this kind is to try and achieve the largest possible opening width with the smallest possible diameter of the fiber collecting groove, which is only possible when the degree of tapering of the fiber sliding surface is kept as low as possible. The tapering angle of the fiber sliding surface should only be so big that the single fibers which are fed to the fiber sliding surface can just about slide into the fiber collecting groove.
Lower taperings of the fiber sliding surface are known in non-generic open-end spinning rotors. In German published patent 196 30 834, an open-end spinning rotor is disclosed in which the degree of tapering of the fiber sliding surface to the rotational axis measures only between 8° and 12°. However, the aim here is to permit the thread formation to take place already on the fiber sliding surface, that is, a sliding of the fibers into a fiber collecting groove arranged downstream does not take place in this case.
Furthermore, in German published patent application 43 04 151, FIG. 20, a totally cylindrical fiber sliding surface is even disclosed. This, however, is provided with a particular surface structure, which exerts a mechanical transporting effect on the fed in single fibers, which is designed to replace the missing centrifugal forces.
In contrast, however, and in accordance with the present invention, a normal sliding of the single fibers on the fiber sliding surface as a result of the centrifugal forces, and without any additional surface structures, should take place.
The diameter of the fiber collecting groove should preferably measure a maximum of 26.5 mm and may even measure only 24 mm. The ratio of the diameter of the fiber collecting groove to the opening width should be between 1.05 and 1.22. In order to ensure that the single fibers reach the fiber collecting groove, the fiber collecting groove is arranged at a distance from the front surface which measures only between 9 and 12 mm.
In order to reach high speeds, it is further provided that in the area of the fiber collecting groove also the outer diameter should measure a maximum of 28 mm. The wall thickness in the area of the fiber sliding surface is, at 1 mm, kept very thin. Despite these small dimensions, a sufficient strength is achieved for the wall of the open-end spinning rotor in that the outer contour in the area of the fiber sliding surface is curved. This curve should run convexly towards the front surface.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.